Ram Angle and Magnetic Field Sensor for Satellite Attitude
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Solution Overview
Problem
Current attitude control systems for picosat-class satellites are costly, large, and power-intensive, and often lack accurate three-axis attitude knowledge, especially during eclipse conditions, as they rely on expensive star trackers or combinations of sun sensors and magnetometers that lose accuracy in eclipse.
Innovation Solution
A Ram Angle and Magnetic field Sensor (RAMS) system that combines a ram sensor for measuring neutral winds with a magnetometer to provide continuous sub-degree three-axis attitude sensing, using a measurement interface module to calculate attitude information, allowing for precise attitude determination regardless of sunlight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If star trackers are used for precise attitude knowledge, then measurement precision is improved, but device complexity, weight, and power consumption increase significantly
Solution Approach 1:
The patent combines a RAM sensor and magnetometer into a single integrated attitude sensing system. The RAM sensor measures the angle between the satellite's velocity vector and the geomagnetic field, while the magnetometer measures the magnetic field direction. This merging of two simpler sensors achieves the attitude determination function that would otherwise require a complex star tracker system.
Solution Approach 2:
The RAM sensor serves dual purposes: it measures attitude information by detecting the angle between velocity and magnetic field, and simultaneously provides space weather data about thermospheric winds. This multi-functionality eliminates the need for separate dedicated sensors, reducing overall system complexity while maintaining precision.
2Ease of manufacture
If sun sensors and magnetometer combination is used, then cost is reduced, but reliability deteriorates during eclipse conditions when sun information is lost
Solution Approach 1:
The RAM sensor acts as an intermediary that provides continuous attitude reference regardless of sunlight conditions. By measuring the angle between the velocity vector and geomagnetic field, it maintains reliable operation during eclipse when sun sensors fail, bridging the reliability gap without requiring expensive star trackers.
3Device complexity
If simple magnetic control is used for attitude alignment, then device complexity is reduced, but measurement precision deteriorates to only magnetic field line alignment without three-axis control
Solution Approach 1:
The patent adds the dimension of velocity vector orientation by using the RAM sensor to measure the angle between the satellite's velocity and the magnetic field. This additional dimensional information, combined with magnetometer data, enables full three-axis attitude determination while maintaining relatively simple system architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The RAMS system offers a cost-effective, compact, and power-efficient solution for continuous attitude sensing, providing accurate three-axis attitude knowledge using in-situ measurements of ram direction and magnetic fields, enabling precise attitude control without the need for expensive star trackers and maintaining accuracy throughout the orbit, including eclipse conditions.
Implementation Method 1
The neutrals are then ionized in a thermionic cathode chamber before passing into a free drift vacuum chamber
Implementation Method 2
The neutrals are then ionized in a thermionic cathode chamber
Implementation Method 3
a magnetometer configured to measure a geomagnetic field
Data Source
AI summary
A method and system is described for determining attitude for a satellite. A two-axis ram sensor head measures neutral winds and provides a density of the neutral winds. A three-axis magnetometer measures a geomagnetic field. A measurement interface module calculates attitude information, which includes three-axis attitude knowledge of a satellite relative to a local-vertical local-horizontal orbit frame, based on the combined ram measurements and magnetic field measurements, and provides the attitude information to a satellite that comprises the attitude sensor system.